Help Please! I’ve purchased a Geo system that I have to learn to tweek because the service people performing the routine checks clearly don’t know what they’re doing. (the last guy tried to take pressure readings w/ a gauge that had increments of 5psi). I’m not seeing hardly any decrease in total power bill despite going from a 15-20 year old 80% efficiency gas furnace/AC. My new system is a NDV038A111CTR w/ hot water generator, preheat tank and a closed 350 ft SDR11 polyethylene plastic loop (3/4 inch outside the house, 1.25 inch inside) filled w/ 21% methanol in a horizontal loopfield with the loop spaced 10 feet apart, and I’m located in Indianapolis w/ somewhat sandy soil since I’m not far from a river. In reading this forum and there seems to be some debate about what is the optimal flowrate for efficiency, some thinking the faster the better, some saying stay within the range on the installation manual(2.5-3.0GPM/ton… in the case of my unit 7.9-9.5gpm), and the manufacturer saying set it at 9.0GPM (but I’m guessing this is a balance between efficiency and unit safety, longevity). My loop installer seems to be the most knowledge person among the Heating and Cooling company’s service techs and the Waterfurnace tech service department… and he thought 9.0gpm was ideal in the summer, but a slower rate is better in the winter….thinking that a fast flowrate in the summer allows heat to be taken out of the house faster, but a slower flowrate allows more heat to be picked up from the loopfield in the winter. 1) Does anyone have more thoughts on what is the optimal flowrate? If not, do I just find it experimentally by finding the greatest temperature difference in return and supply via testing different loop flows? 2) If a slower flow rate does turn out to be more efficient, I believe I heard that there are certain problems that I need to look out for (faults,etc). Can anyone elaborate on this (and would the warning signs, issue be different in summer than the winter?) I guess I’m going to be making some purchases in order to be able to test flowrate. Will probably buy the following: [*]a cheap clamp-around amp meter to make sure I'm in Stage 2 when testing [*]A SISCO GA-125 gauge adapter [*]Either a 100 psi gauge with 1 psi increments or a GPDW-08 digital gauge (0.1psi increments) [*]A snubber if pressure fluctuation is too much to get a good estimation. [*]Temperature probe(s) with 0.1F increments for water readings and return/supply air readings. 3) On the temperature probe, does anyone have any recommendations? Any advice is appreciated.